The present invention relates generally to welding wires for use in gas metal arc welding of steels, and more particularly to a chemically balanced iron based welding wire which provides for increased ease of drawing the wire, improved welding productivity and improved weld deposit properties and appearance.
Two commonly utilized field welding processes are shielded metal arc which utilizes coated stick electrodes and gas metal arc which utilizes bare wires or filler wires. The present invention relates to a chemically balanced composition for the bare or filler wires containing carbon, manganese, silicon, with restricted and controlled trace amounts of such elements as phosphorus, sulfur and copper.
For at least the last twenty years, filler wires containing each of the above identified elements have been manufactured and offered for sale to the welding industry. One such filler wire, identified as ER 70S-2, is one example of such a low alloy filler wire which contains a low silicon content. Because the ER 70S-2 wires contain reduced amounts of silicon, such types of filler wires are not well suited for deoxidizing welds on oily or dirty steels unless special expensive additives (aluminum, zirconium or titanium) are added to the alloy and such wires do not optimize the weld bead contours when the appearance of the weld is important in the finished part.
Another low alloy filler wire is known as ER-70S-6 which possess improved welding characteristics such as good wetting characteristics, low spatter levels and good weld deoxidation. However, because the ER 70S-6 wires contain higher carbon and manganese ranges, the increased carbon and manganese contents result in difficulties in drawing the wire and require the additional step of patenting or heating the wire either before or during the drawing operations. Thus, such filler wires are expensive to manufacture and result in a more costly filler wire.
Finally, a European filler wire material, identified as BS2901 Code A-18, which is nearly chemically equivalent to the AWS classification ER 70S-6, contains a typical composition of 0.1 weight percent carbon, 1.5 weight percent manganese, 0.85 weight percent silicon, 0.015 weight percent sulfur and 0.015 weight percent phosphorus. Although such filler wires exhibit good wetting characteristics and low spatter levels, the higher carbon and manganese content cause difficulties during manufacturing the wire because of the additional step of patenting or heating the wire before or during the drawing process. Accordingly such wires are expensive to manufacture.